Letter to the Editor: Acute rejection after liver transplantation with machine perfusion versus static cold storage: A systematic review and meta-analysis

Reply: Acute rejection after transplantation of machine perfused livers—We have barely scratched the surface

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We thank Liang et al [1] and Neil et al [2] for their letters regarding our recent meta-analysis on acute cellular rejection after liver transplantation with dynamic preservation versus static cold storage. [3] We appreciate the literature review conducted by Liang et al [1] although the mentioned studies were either excluded from our meta-analysis because they did not meet our inclusion criteria or were published after our literature search had already been completed.

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We thank Liang et al [1] and Neil et al [2] for their letters regarding our recent meta-analysis on acute cellular rejection after liver transplantation with dynamic preservation versus static cold storage. [3] We appreciate the literature review conducted by Liang et al [1] although the mentioned studies were either excluded from our meta-analysis because they did not meet our inclusion criteria or were published after our literature search had already been completed. The authors are correct that Nasralla et al [4] state in their protocol that they will record biopsy-proven acute cellular rejection as a safety outcome; however, Extended Table 6, which summarizes all adverse events, only mentions "rejection".We commend the Birmingham group for their interesting work on retransplantation with "suboptimal liver grafts" after normothermic machine perfusion (NMP).

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“…We thank Liang et al 1 and Neil et al 2 for their letters regarding our recent meta-analysis on acute cellular rejection after liver transplantation with dynamic preservation versus static cold storage 3 …”

“…We appreciate the literature review conducted by Liang et al 1 although the mentioned studies were either excluded from our meta-analysis because they did not meet our inclusion criteria or were published after our literature search had already been completed. The authors are correct that Nasralla et al 4 state in their protocol that they will record biopsy-proven acute cellular rejection as a safety outcome; however, Extended Table 6, which summarizes all adverse events, only mentions “rejection”.…”

The conclusion of reducing acute rejection after liver transplantation by machine perfusion should be extrapolated with caution

“…There is a theory that the unavoidable graft damage caused by ischemia-reperfusion injury (IRI) during liver transplantation (LT) can lead to severe IRI-related inflammation and trigger an early activation of the innate immune response mediated by T-cells, which potentially worsening the acute cellular rejection (ACR) cascade. As a result, machine perfusion (MP) has been placed great expectations for the potential to diminish post-LT ACR and other related immune responses by alleviating IRI through removing harmful substances and restoring cellular metabolism homeostasis ( 1 , 2 ). However, there has been much debate about MP’s benefits on ACR as relative data is limited.…”